A substrate processing apparatus having a configuration in which pressure measuring parts are installed corresponding to the number of types of gases supplied into a processing chamber is known in the conventional art. The processing chamber receives substrates such that each substrate is dedicated to the respective gases, and a film is not formed on a diaphragm sensor that constitutes each of the pressure measuring parts so as not cause an error in measured pressure values.
In addition, a pressure measuring device is know in the art in which a circular plate is installed at a position facing a diaphragm to form an annular flow path, and a solid substance adheres to a place at which the diaphragm is less affected by stress, so that the effect of the stress occurred by the adhered solid substance on a deformation of the diaphragm is reduced.
However, such configurations, although possible to reduce the occurrence of an error in a pressure gauge, fail to accurately recognize the error of the pressure gauge. To address this requires periodically checking a shifted amount of the pressure gauge and periodically performing a zero-adjustment by which the pressure gauge is reset to zero in a state where a processing chamber is exhausted up to a maximum vacuum level.
Such zero adjustment is an approximate-level compensation in which the pressure gauge is reset to zero when a vacuum level is maximum, namely closest to zero), rather than accurately recognizing an error or shifted amount of the pressure gauge and performing a compensation based on the recognized result. This configuration fails to accurately compensate the pressure gauge. There is another technique for connecting a high precision pressure gauge during maintenance and compensating an erroneous pressure gauge by identifying a difference between these pressure gauges. In any case, it is impossible to accurately check a replacement time of the erroneous pressure gauge. Thus, only an ex-post measure that the erroneous pressure gauge is initially replaced when some problems occur, were possible.